I missed this (due to my station airing Sesame Street minutes before I leave for school). It's very rare that they show older episodes of Sesame Street on any PBS station. I remember when I last watched it, the re-runs were either A. episodes from the latest season or B. episodes from the previous season.
Also, wasn't this one of the episodes they aired after 9/11 to help kids cope with the tragic events? There were also two other episodes like this, the one with the grease fire at Hooper's store and the one with the bird who didn't want to be bullied or something.
Also, last year, the Japanese show Suite Pretty Cure did something like this to help kids cope with the March 11th earthquake and tsunami by changing the plot so that the Melody of Sorrow got completed first.